Hi Peter
On 1/27/21 12:54 PM, Peter Zijlstra wrote:
On Wed, Jan 27, 2021 at 02:25:38PM +0530, Anshuman Khandual wrote:
It is possible to have a perf session where some events end up collecting the trace in TMC-ETR while the others in TRBE. Thus we need a way to identify the type of the trace for each AUX record.
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 9a5ca45..169e6b3 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -1111,6 +1111,10 @@ enum perf_callchain_context { #define PERF_AUX_FLAG_COLLISION 0x08 /* sample collided with another */ #define PERF_AUX_FLAG_PMU_FORMAT_TYPE_MASK 0xff00 /* PMU specific trace format type */ +/* CoreSight PMU AUX buffer formats */ +#define PERF_AUX_FLAG_CORESIGHT_FORMAT_CORESIGHT 0x0000 /* Default for backward compatibility */ +#define PERF_AUX_FLAG_CORESIGHT_FORMAT_RAW 0x0100 /* Raw format of the source */
Would CORESIGHT_FORMAT_ETR / CORESIGHT_FORMAT_TRBE be better names?
Not really. The format used by the ETR is CORESIGHT frame formatting. And there are other sinks that uses the formatting. e.g, TMC-ETB (a sink with internal memory), TMC-ETF (trace fifo with internal memory). So it is really not tied to ETR.
As for TRBE, it simply pumps the data thrown at it to the memory. As such calling it TRBE format would be confusing as the format of the buffer is really Raw trace thrown at it. This can be inferred from the ETM/ETE looking at the ID registers, which the userspace perf already captures in the perf.data. So the decoder perf can look at the perf.data and the AUX records to interpret the buffer correctly.
Suzuki